This invention relates to methods and apparatus for releasing a parachute from an aircraft. One application of the invention illustrated and described herein pertains to parachute release apparatus for use with an aerial cargo delivery system, wherein the apparatus releases a drogue or extraction parachute from a cargo carrying aircraft, although the invention may be utilized in other applications or environments.
The type of aircraft with which this invention may be used typically includes a raised tail assembly and a cargo space which opens aft and below the tail assembly for purposes of loading, unloading and aerial cargo delivery. Examples of such aircraft are the C-119, C-123, C-130, C-141, and C-5A. To effect an aerial cargo delivery, a drogue parachute is deployed from the open aft end of the cargo space to exert an extraction force on the cargo or load contained therein. This extraction force pulls the cargo rearwardly from the aircraft through the open aft end of the cargo space. For high altitude airdrop, additional recovery parachutes are then deployed from the cargo. For low altitude airdrop, (often referred to as "LAPES" airdrop), the cargo descends to the ground without deployment of recovery chute(s). In either system, the extraction force is applied to the cargo by an extraction parachute(s) through a force transfer device, commonly referred to as a "tow plate."
Cargo aircraft of the type described currently use a "bomb-rack" pendulum pivot release mechanism to deploy the drogue or extraction parachute. This mechanism includes a pendulum pivot which is mounted in the interior crown of the cargo space ceiling, usually at a height greater than 10 inches above the floor of the cargo space, and a parachute holder which is supported from the ceiling of the cargo space forward of the pendulum pivot. The parachute is attached to one end of a pendulum line, the other end of which is secured to the pivot. The pivot provides a suspension point located to the rear of the open aft end of the cargo space and is cut away or relieved at its aft end to permit the other end of the cable to separate therefrom upon swinging aft beyond approximately vertical. The parachute holder includes spaced-apart hooks, which engage appropriate rings or other fasteners on the parachute, together with a release mechanism for opening the hooks to release the parachute. In the operation, the pendulum first is attached to the pivot and then is positioned with its length extending forwardly along the ceiling of the cargo space. The parachute then is secured to the parachute holder and is held thereby adjacent to the aircraft ceiling. Upon release from the parachute holder, the parachute swings by gravity on the pendulum in an aft direction and out of the open aft end of the cargo space, whereupon the cable separates from the pivot to effect separation of the parachute from the aircraft.
The pendulum pivot release mechanism is unsatisfactory in many practical applications. Since the pendulum is located beyond the normal reach of the load master standing on the floor of the cargo space, the load master must lower the parachute holder to the floor in order to load the parachute thereon. He then must raise the parachute and the holder toward the ceiling of the cargo space, must stand on an appropriate step support to attach the pendulum cable to the pendulum pivot and, finally, must lash the parachute line to an appropriate line restraint fitting on the floor of the cargo space. The proximity of the cargo doors and/or cargo ramp at the aft end of the cargo space poses a significant safety hazard to the load master so that, in most practical cases, both are closed prior to and during parachute loading, as well as while rerigging the parachute release system during multiple airdrops, increasing drop zone time. Furthermore, since the mechanism is made up of two separate assemblies (i.e. the fixed pivot or release mechanism, and a parachute holder), precise rigging and operational sequencing must be followed in order to ensure a successful parachute release. In many practical applications, operational reliability of the parachute release system therefore tends to be unsatisfactory.
In the YC-14 cargo aircraft, fabricated by the assignee of the present invention, the aforementioned pendulum release mechanism is highly undesirable because the body of the aircraft is somewhat wider than standard cargo aircraft of the type described and the overhead location required for the pendulum release pivot is above the cargo door. As a consequence, secondary structure are required to support the pendulum pivot and the load master cannot reach it from the cargo space floor, even when supported on a step support. To attach the pendulum cable to the pendulum pivot, therefore, the load master must climb upward along the inside of the closed cargo door. Additionally, since the pendulum release pivot must be moved clear of the cargo door when the cargo door is opened and closed, the secondary structure in order to provide such movement tends to be complex, with attendant uneconomical fabrication and maintenance costs.